Binder for separator of non-aqueous electrolyte battery comprising 2-cyanoethyl group-containing polymer and separator and battery using the same

Abstract

Object of the invention is to provide a binder for a separator which can be comprised by a non-aqueous electrolyte battery with improved battery properties and heat resistance; the separator comprising the binder; and the non-aqueous electrolyte battery comprising the separator. More specifically, provided is a binder for a separator of a non-aqueous electrolyte battery, the separator comprising a 2-cyanoethyl group-containing polymer having bis-cyanoethyl ether content of 0.5% by weight or less as an impurity.

Description

RELATED APPLICATION[0001]This application claims priority from Japanese Patent Application No. 2011-084067, filed Apr. 5, 2011, the disclosure of which is incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates to a separator of a battery, the separator comprising a porous substrate and a heat-resistant porous layer, wherein the separator comprises a 2-cyanoethyl group-containing polymer having the content of specified impurity limited to a certain value or below as a binder in the heat-resistant porous layer; and a non-aqueous electrolyte battery with improved heat resistance and improved battery properties by using the separator for a battery.[0003]Recently, as a power source for a mobile terminal such as that of a notebook computer or a cellular phone or as a power source for a hybrid car or an electric car, a non-aqueous electrolyte battery with high voltage and high energy density, in particular a lithium ion secondary bat...

AI Technical Summary

Benefits of technology

[0012]As a result of intensive studies, the present inventors have found that bis-cyanoethyl ether present in a 2-cyanoethyl group-containing polymer has a bad influence on heat resistance of a separator of a non-aqueous electrolyte battery; and a binder comprising a 2-cyanoethyl group-containing polymer having an certain amount or less of bis-cyanoethyl ether as an impurity can provide a separator having sufficient adhesion among inorganic filler particles in a heat-resistant porous layer even in an electrolyte solution, and having excellent mechanical strength of a heat-resistant porous layer and favorable ion conductivity. The invention has been completed based on the finding.

[0014]According to the invention, provided are a binder for a separator which can produce a non-aqueous electrolyte battery with excellent battery properties and heat resistance; the separator comprising the binder; and the non-aqueous electrolyte battery comprising the separator.

Problems solved by technology

Thus, there is a problem that heat is generated in the battery due to Joule heat caused by short circuit, the battery is swelled due to gas generation accompanied with decomposition of an electrolyte solution, and properties of the battery are deteriorated.

Thus, in a conventional separator comprising a porous substrate having fine pores such as a polyolefin film, the separator is shrunken or melted by heat generated by the short circuit at the short circuit region so that the battery is exposed to dangers of fuming, ignition and explosion.